This invention relates in general to a novel imaging device and, more specifically, to a novel screen stencil imaging device as well as to a method of preparing and to a process of using said device.
Screen stencil printing is the modern form of one of the oldest of all printing processes. It is a modern development of the principle used by ancient Chinese and Japanese artisans who learned to make very intricate stencils by gluing cut designs to a web of hair, thus making it possible to use isolated elements which could not otherwise be held in place.
In the Middle Ages the art of screen stencil printing spread through Europe for such diverse purposes as religious images and playing cards, and by the Seventeenth Century, stencils were widely used in England for wallpaper decorations. Early American colonists used the technique for placing designs directly upon walls, furniture, textiles, etc. Silk screen printing, as it was called earlier, had no single pioneer but the idea of using a silk fabric as a screen or ground to hold the stencil generally is credited to Samuel Simon of Manchester, England.
As compared with other printing processes, screen stencil printing has several advantages. For example, it is economical for short runs of suitable subjects such as show cards, posters, charts, etc. Further, it permits printing on almost any type of surface. In addition, areas of relatively large size are easily stenciled (frames 50".times.60" are frequently used for textile printing). Finally, since the object to be decorated need not be limited in thickness or even perfectly flat, the process is often used for printing on objects such as toys, novelties, and machinery which could not be run through a printing press.
The screen stencil ordinarily used consists of bolting silk pressed over a wooden frame. On this silk is the design to be stenciled. This design may be produced by manually painting the areas which are to remain white with some substance, such as gum or shellac. This results in making the treated portions of the silk impervious to the ink used. The stencil is placed in contact with the surface to be decorated and a puddle of ink is scraped from one end to the other by means of a rubber squeegee. This forces the ink through the open areas of the stencil and it adheres to the surface beneath. The stencil is then lifted from the decorated surface and the ink is allowed to dry, after which another color may be applied from another stencil, and so on.
The basic method described above is widely used as a hobby craft, as well as an art medium. In recent years more sophisticated method of making stencils and printing have come into use. For certain purposes, wire gauze or cotton fabrics may be substituted for the bolting silk, and a number of methods have been devised for putting the design on the screen. Fine detail in the pattern generally makes it advisable to make the stencil photographically by impregnating the screen with a light sensitive material such as dichromated glue to albumin, and exposing it to light under a tracing of the pattern. The image is developed by washing with water, which removes the coating from the open areas where it has not been light-hardened. Simple designs are often made by cementing patterns cut from paper, celluloid, or metal, to the screen, a common method being to cut the design from shellac-coated paper and fasten it to the core by pressing a hot iron over the two in contact.
Although there are several advantages associated with screen stencil printing, the process, as it is known today, also has decided disadvantages. For example, one drawback of screen stencil printing is that it is quite time-consuming. One must laboriously coat the screen with gum, shellac, etc., and then allow a set amount of time for drying and rinsing. Even when said stencil is made photographically, using materials such as dichromated glue, the manual process of coating said stencil is not eliminated. Thus, there is a continuing need for novel screen stencils and processes for preparing and using same which are economical, time-saving, and which require a minimum of manual work.